Bioaccumulation and toxicology of chromium: implications for wildlife

Concentrations of iron and chromium in free-ranging common marmosets (Callithrix jacchus) from Pernambuco, Brazil

Common marmosets (Callithrix jacchus) are widely distributed in Northeast Brazil and often inhabit urban and peri-urban forest areas close to human settlements. Given its wide territorial distribution, its proximity to human populations, and its exposure to environmental degradations originating from urbanization, common marmosets have a high potential for environmental biomonitoring. The concentrations of iron (Fe) and chromium (Cr) were quantified in the liver, hair, and bone of 22 free-ranging common marmosets' bodies from nine cities from Pernambuco State, Brazil, using inductively coupled plasma optical emission spectrometry (ICP OES). The liver showed the highest concentrations of Fe and Cr (3773.2 ± 3715.8 mg/kg and 19.4 ± 41.6 mg/kg, respectively); the lowest concentration of Fe was detected in the bone (111.6 ± 97.6 mg/kg) and of Cr in the hair (3.3 ± 1.5 mg/kg). There was a moderate positive correlation between Fe and Cr in the liver (r = 0.64) and a high negative correlation for Cr between bone and hair (r = -0.65). This study demonstrated the bioaccumulation of Fe and Cr in hair, liver, and bone in common marmosets. The highest average concentration of Fe and Cr occurred in animals from Recife, Jaboatão dos Guararapes, and Paulista, respectively, the 1^st, the 2^nd, and the 5^th most populated cities in the state of Pernambuco. The presence of high concentrations of metals in animals from Recife and nearby cities can indicate alarming levels of environmental pollution in these locations.

Exposure to e-cigarette aerosol over two months induces accumulation of neurotoxic metals and alteration of essential metals in mouse brain

Despite a recent increase in e-cigarette use, the adverse human health effects of exposure to e-cigarette aerosol, especially on the central nervous system (CNS), remain unclear. Multiple neurotoxic metals have been identified in e-cigarette aerosol. However, it is unknown whether those metals accumulate in the CNS at biologically meaningful levels. To answer this question, two groups of mice were whole-body exposed twice a day, 5 days a week, for two months, to either a dose of e-cigarette aerosol equivalent to human secondhand exposure, or a 5-fold higher dose. After the last exposure, the olfactory bulb, anterior and posterior frontal cortex, striatum, ventral midbrain, cerebellum, brainstem, remaining brain tissue and spinal cord were collected for metal quantification by inductively coupled plasma mass spectrometry and compared to tissues from unexposed control mice. The two-month exposure caused significant accumulation of several neurotoxic metals in various brain areas - for some metals even at the low exposure dose. The most striking increases were measured in the striatum. For several metals, including Cr, Cu, Fe, Mn, and Pb, similar accumulations are known to be neurotoxic in mice. Decreases in some essential metals were observed across the CNS. Our findings suggest that chronic exposure to e-cigarette aerosol could lead to CNS neurotoxic metal deposition and endogenous metal dyshomeostasis, including potential neurotoxicity. We conclude that e-cigarette-mediated metal neurotoxicity may pose long-term neurotoxic and neurodegenerative risks for e-cigarette users and bystanders.

Heavy metal contamination in wild avian species inhabiting human-modified habitats

Health of birds and heavy metal toxicity are growing concerns in Pakistan because of irresponsible industrial waste management and farming practices. Eight species of common wild birds were studied from three different study sites which varied in the type of environmental pollution (Kasur: industrial waste, Lahore city: traffic pollution and Shahdara: mixed pollution of traffic, sewerage, and industry which the Ravi River accumulates). Heavy metal analysis of six heavy metals in the various organs of birds showed that there was no evidence of organ preference for metal accumulation in birds. Shahdara and Kasur with numerous industries both showed chromium concentrations above toxicity levels in 54.16% tissues of Granivorous birds, 60% of omnivorous birds, and 33.33% in tissues of carnivorous species. Statistical analysis proved that there is no correlation between weight of birds and accumulation of metals; it depends on food preference of birds and properties of the metals as bioaccumulators or biomagnifiers.

Contaminated Land by Wildfire Effect on Ultramafic Soil and Associated Human Health and Ecological Risk

The purpose of this study is the evaluation of fire effect on contaminated land and the assessment of the associated risk of human health and terrestrial ecological receptors. Ash and soil samples were gathered from burned and unburned areas (central Evia, Greece) which are adjacent with a Natura 2000 area. The geochemical dataset includes 20 sampling sites and 35 elements. The wildfire severity was investigated by applying a macroscopic approach and field observations. Statistical and spatial analysis were applied for delineating the distribution of elements in ash and soil. Elemental balance approach was performed for estimating net gain (+) or loss (−) to the ash. Element contents in sampling sites were compared to screening values proposed by the literature. Hundreds of hectares of burned land including wildland areas in central Evia are contaminated with (contents in mg Kg−1), Co (up to 43.5), Cr (up to 244), Mn (up to 1158), Ni (up to 463) associated with geogenic sources such as serpentinite peridotites and Ni-laterite deposits. Aluminum, As, Cd, Co, Cr, Fe, Mn, Ni, Pb, V and Zn contents recorded in the sampling sites are posing a potential risk to human health and ecological receptors.

Is blood a reliable indicator of trace metal concentrations in organs of small mammals?

In wildlife ecotoxicology, the rationale for using blood rather than other body fluids or tissues is that sampling blood is a minimally invasive technique without animal mortality, providing both ethical and scientific benefits. To date, few studies are available on the relationships between blood and organ metal concentrations of small mammals living in contaminated sites. The present work aimed to study the relationships between the concentrations of 18 essential and nonessential metals in blood and their concentrations in the liver and kidneys, two accumulation and target organs, in wood mice from a former lead and zinc smelter, Metaleurop Nord, in northern France. The results from Se, Pb and Tl indicate that blood levels may be used to predict concentrations in organs of small mammals. Conversely, for Cd, Cu, Fe, Mo, Ti and Zn, blood concentrations were poorly or not related to liver and kidney concentrations. In addition to accurately predicting the concentrations of some metals in target organs, blood can provide important information about the physiological and biochemical status of organisms, but further toxicokinetic research is required to develop the use of blood sampling as a minimally invasive biomonitoring and ecotoxicological method in wildlife.

An Adult Zebrafish Diet Contaminated with Chromium Reduces the Viability of Progeny

The lack of standardized diet for laboratory animals can have profound effects on animal health and lead to less reproducible research outcomes. Live diets are commonly used in zebrafish culture and, although they are a more natural feed than flake or pellet food, are also a potential source of pathogens and toxic compounds. Heavy metals are a group of such compounds, which can accumulate in fish leading to developmental abnormalities, reduced growth, and increased rates of mortality. Two to three weeks after feeding adult zebrafish a new lot of nonhatching decapsulated brine shrimp cysts (Decaps), embryos at the University of Minnesota Zebrafish Core Facility (ZCF) and the University of Utah Centralized Zebrafish Animal Resource (CZAR) began to exhibit an orange color in the yolk, and larval health began to decline. The concentration of chromium in the Decaps (69.6 mg/kg) was more than 30 times that of other zebrafish diets tested (up to 2.1 mg/kg) and is thought to be the cause of the observed symptoms. Within 3 weeks of removing the Decaps from the feeding regimen, the orange coloration in the yolks began to diminish, the morphological abnormalities began to subside, and larval survival rates began to increase. Thus, implementation of standardized zebrafish diets and regular feed-quality testing may help to prevent the introduction of contaminants to zebrafish research facilities.

Mutagenic and genotoxic effects and metal contaminations in fish of the Amambai River, Upper Paraná River, Brazil

The present study evaluated mutagenic and genotoxic effects and metal accumulation in the liver and musculature of Pterygoplichthys ambrosetti and Prochilodus lineatus in the Amambai River, a tributary of the Upper Paraná River in Brazil. We also evaluated the potential for these fish species as environmental bioindicators and performed risk assessment for conservation purposes. We found that P. ambrosetti had a higher frequency of micronuclei compared to P. lineatus (p < 0.0001). There were no significant differences between species in other erythrocyte nuclear abnormalities (ENA) (p > 0.05). For both species, the liver contained a higher concentration of metals (Cd, Pb, Cr, Cu, Fe, Zn, and Ni) than the musculature did (p < 0.0001). Of the two species, P. ambrosetti was more suitable to evaluate mutagenic and genotoxic effects and metal accumulation in the liver and musculature, likely due to its resident behavior; hence, we highlight the potential of this species for use as an environmental bioindicator. The concentrations of non-essential metals observed in the fish confirm conditions of environmental stress in the Amambai River, possibly related to the discharge of pollutants and exacerbated by lack of native vegetation cover along the watercourse.

The effect of dietary organic chromium on specific growth rate, tissue chromium concentrations, enzyme activities and histology in common carp, Cyprinus carpio L

A 63-day feeding trial was carried out to investigate the effect of three levels of Cr yeast (0.5, 1.0 and 2.0 mg Cr/kg) on the utilization of diets containing 38.5 % of maize starch or dextrin in common carp, Cyprinus carpio L. (initial mean body mass 14 ± 0.3 g) in an auto circulator system at 25 ± 0.5 °C. A two-way analysis of variance (ANOVA) showed that the final body mass (FBM), percentage mass gain (%MG), specific growth rate (SGR) and feed conversion ratio (FCR) were significantly (P < 0.05) affected by the two sources of variation (carbohydrate source and Cr level). In general, fish fed on a diet containing starch and fortified with 0.5 mg Cr/kg performed significantly higher FBM (47.23 g), %MG (225.11), SGR (1.91) and lower value of FCR (1.24) compared to fish fed on the other diets. Carp fed on 2.0 mg Cr/kg with maize starch and 1.0 mg Cr/kg with dextrin-based diet showed a significant reduction (P < 0.05) in whole body lipid content as confirmed by a two-way ANOVA. Fish fed on a maize starch-based diet supplemented with 0.5 and 1.0 mg Cr/kg recorded the highest activities for hexokinase enzyme. Glucose-6-phosphate dehydrogenase activity was neither affected by Cr concentration nor by dietary carbohydrate source. Fish fed on dextrin-based diets accumulated higher Cr in the whole tissue compared to fish fed on starch-based diets. Normal histological structures in the liver and gut tissues were observed in all groups. The present data clearly showed that dietary Cr yeast was safe in the fish diet at the levels tested.

Cr(VI) induces lipid peroxidation, protein oxidation and alters the activities of antioxidant enzymes in human erythrocytes

The effect of potassium dichromate (K(2)Cr(2)O(7)), a hexavalent chromium compound, on human erythrocytes was studied under in vitro conditions. Incubation of erythrocytes with different concentrations of K(2)Cr(2)O(7) resulted in marked hemolysis in a concentration-dependent manner. K(2)Cr(2)O(7) treatment also caused significant increase in protein oxidation, lipid peroxidation and decrease in total sulfhydryl content, indicating that it causes oxidative stress in human erythrocytes. However, there was no concomitant nitrosative stress as the nitric oxide levels in hemolysates from K(2)Cr(2)O(7)-treated erythrocytes were lower than in control. Exposure of erythrocytes to K(2)Cr(2)O(7) decreased the activities of catalase, glutathione peroxidase, thioredoxin reductase, glucose-6-phosphate dehydrogenase, and glutathione reductase, whereas the activities of Cu-Zn superoxide dismutase and glutathione S-transferase were increased. These results show that K(2)Cr(2)O(7) induces oxidative stress and alters the antioxidant defense mechanism of human erythrocytes.

Metals in liver and kidneys and the effects of chronic exposure to pyrite mine pollution in the shrew Crocidura russula inhabiting the protected wetland of Doñana

Historically impacted by anthropogenic activities, the nature reserve of Doñana (SW Spain) was affected by an unprecedented spillage of mud and acidic water from the Aznalcóllar pyrite mine in April 1998. Although several studies have addressed the influence of this spill on soils, water, and biota, there is little information on mammals, especially carnivorous species. We measured the concentrations of Fe, Mg, Pb, Hg, Cd, Zn, Cu, Mn, Mo, Co, and Cr in specimens of the greater white-toothed shrew, Crocidura russula, inhabiting the protected area affected by the mine spillage. We also examined other parameters to approach at the physiological effects of pollution. We found an increase in non-essential metals (Pb, Cd, and Hg), and morphometric, histological and genotoxic alterations. Age and gender were two significant factors explaining metal bioaccumulation: adults had higher Hg and Cd levels than juveniles, whereas males bioaccumulated more Pb and Co and less Mo than females. The micronucleus frequencies in blood erythrocytes were significantly higher in specimens from the polluted site than animals from the control site. Shrews from the impacted area also had hepatic alterations, namely increased liver-body ratio, focal necrosis, and signs of apoptosis in hepatocytes. Due to the relevance of small mammals in the diet of endangered species such as carnivorous birds and mammals, the findings of our study are of practical use for the management of the Doñana wildlife reserve and other protected Mediterranean wetlands.

Metal accumulation in cattle raised in a serpentine-soil area: relationship between metal concentrations in soil, forage and animal tissues

Soils developed on serpentine rocks contain high levels of heavy metals such as copper (Cu), nickel (Ni) and chromium (Cr), and are deficient in some macronutrients. The crops and pasture grown on these soils may accumulate high levels of metals, which constitute a potential health hazard for cattle. The aim of this study was to evaluate Cr, Ni and Cu accumulation in cattle raised in a serpentine area in Southwest Europe (Galicia, NW Spain). Samples of liver, kidney and muscle of 41 animals aged 8-12 months were collected at slaughter. Representative samples of soil and forage were taken from 10 farms. Samples were acid-digested and metal concentrations determined by ICP-MS (Cr and Ni) and ICP-AES (Cu). The concentrations of the metals in soils and forage were in the range of those found in serpentine soils in other areas. Accumulation of Cr in animal tissues was generally low and within the normal range. However, 20% of the animals had toxic levels of Ni in kidney and 32% of the animals had liver Cu levels above the acceptable range. Serpentine soils had a significant effect on Ni and Cu accumulation in cattle, and a relatively high percentage of the animals showed tissue levels of Ni and Cu indicative of risk of toxicity.

Bioaccumulation of metals and effects of a landfill in small mammals. Part II. The wood mouse, Apodemus sylvaticus

We assess the bioaccumulation of metals (Pb, Hg, Cd, Fe, Mg, Zn, Cu, Mn, Mo, Cr) and effects of landfill leachates on morphological (RI, relative weights), plasma (GPT, GOT, creatinine), and genotoxic (MNT) parameters in wood mice, Apodemus sylvaticus, inhabiting close the Garraf landfill site (NE Spain). Due to the high age- and sex-dependent variation in wild populations, we also studied the effect of these biotic factors on the parameters studied. Wood mice from the landfill site, sited in a partially protected area, showed more Cd, Fe, Zn, Cu, Mn, Mo, and Cr than specimens from the reference site. Moreover, mice near the landfill registered low RI and high relative renal weight, GPT, and MN frequency, which indicate that the landfill affects the health of wild mice. In contrast to sympatric shrews from a previous study, wood mice showed lower bioaccumulation of metals and lower variation caused by biotic factors. Moreover, the morphological and physiological alterations demonstrated that they were also more sensitive at environmental pollution. Given the contribution of small mammals to ecosystem function and the scarce ecotoxicological data on the effects of landfill pollution on wild terrestrial mammals, we consider that our study can be used to improve the management of this protected area.

Bioaccumulation of metals and effects of landfill pollution in small mammals. Part I. The greater white-toothed shrew, Crocidura russula

Here we quantified the bioaccumulation of metals (lead, mercury, cadmium, iron, magnesium, zinc, copper, manganese, molybdenum, and chromium) and assessed several morphological (RI, relative weights) and genotoxic parameters as biomarkers of pollution from the landfill of Garraf (Barcelona, NE Spain). Specimens of Crocidura russula (Insectivora, Mammalia) from the landfill site showed increased Pb, Cd, Mg, Zn, Cu, and Cr concentrations in their tissues. Levels of mercury were below detection limits. Concentrations of Cd, Pb, and Cr varied significantly with age and no differences were found between males and females. While no differences were found in morphological parameters between shrews from the two sites, those from the polluted one showed more micronuclei in blood than those from reference site (1.786+/-0.272 vs. 0.088+/-0.045 per thousand; U=46.000, p<0.001). The considerable amounts of potentially toxic metals (Pb till 59.71 and Cd till 56.57microgg(-1) DW in kidneys) and the genotoxic effects indicate the harmful effect on biota. We consider necessary biomonitoring this landfill sited in a partially protected area.

Characterization of a simple bacterial consortium for effective treatment of wastewaters with reactive dyes and Cr(VI)

A microbial consortia consisting of three bacteria isolated from tanning and textile wastewaters revealed high capacity to simultaneously bioaccumulate dye and Cr(VI). The identity of the bacteria were determined by 16S rRNA gene analysis to be closely related to Ochrobactrium sp., Salmonella enterica and Pseudomonas aeruginosa. Dependence of initial pH values and range of concentrations of the dye Reactive Black B (33.2-103.1 mg l(-1)) and Cr(VI) (19.9-127.6 mg l(-1)) were examined to find the effect of pH on the dye and Cr(VI) bioaccumulation. Optimal pH for growth of the consortia in media containing 35 mg l(-1) dye and 50 mg l(-1) Cr(VI) was determined to be around 8. The Cr(VI) bioaccumulation by the consortia was rapid in media containing molasses with or without reactive dye with a maximum Cr(VI) bioaccumulation yield ranging from 90% to 99% within a 2-4d period. A slightly lower yield for the dye bioaccumulation was measured with a maximum dye bioaccumulation of 80% at 59.3 mg l(-1) dye and 69.8 mg l(-1) Cr(VI). The highest specific Cr uptake value was obtained as 76.7 mg g(-1) at 117.1 mg l(-1) Cr(VI) and 50.8 mg l(-1) dye concentration. This ability to bioaccumulate dye and Cr(VI) was more efficient than the enriched sludge from which they were isolated.

Metal bioaccumulation in the greater white-toothed shrew, Crocidura russula, inhabiting an abandoned pyrite mine site

Hepatic and renal concentrations of iron, magnesium, zinc, lead, copper, manganese, mercury, cadmium, molybdenum, chromium, and nickel were quantified in shrews (Crocidura russula) inhabiting a pyrite mine site in Portugal. Several morphological parameters (body weight, residual index, and relative weights) were also examined to clarify the physiological effects of pollution. Shrews from the mine showed increased bioavailability of Fe, Pb, Hg, Cd, Mo, and Ni in comparison with reference specimens. Adult shrews had the highest Cd levels while Cr and Ni concentrations diminished. Intersexual differences were found for Mo and Ni. As a consequence of metal pollution, the relative hepatic weight was higher in shrews from the mine site when compared with reference specimens. These data indicate that C. russula is a good bioindicator of metal pollution. We also evaluated the toxic effects of Pb, Hg, Cd, and Ni, because several shrews from the polluted site showed high concentrations of these metals. To approximate at the real biological impact of abandoned mines, after this first step it is necessary to associate the bioaccumulation levels and morphological effects with other physiological, ecological and genetical biomarkers.

Organochlorine and heavy-metal contaminants in wild mammals and birds of Urbino-Pesaro Province, Italy: an analytic overview for potential bioindicators

Tissue samples from 56 bird and 11 mammal species of different trophic levels, collected from 1994 to 1995 from the Urbino-Pesaro area in the Marche region of central Italy, were analyzed for the presence of organochlorine compounds (polychlorinated biphenyls and p,p'-DDE) and heavy metals (Pb, Cd, Cr, and Hg). Results revealed interspecies differences in pollutant residue concentrations. A clear relationship between contaminant and trophic levels emerged depending on several factors specific to the chemicals and the organisms, the importance of dietary accumulation, and metabolic capacity as it increased toward higher trophic levels. Polychlorinated biphenyls and p,p'-DDE were found in all of the bird and mammal species analyzed (bird- or fish-eating birds), and insectivore mammals showed the highest level of these contaminants. Pb and Hg residues were also widely detected and reflected trophic-level differences. The highest concentration of Pb was found in herbivorous or bird-eating aquatic invertebrates and in insectivorous mammals, particularly in the hedgehog (Erinaceus europaeus), whereas the highest Hg levels were found in fish-eating birds. All of the other heavy metals were detected at low concentrations and represented background levels for birds and mammals, with the exception of increased amounts of Cd and Cr, respectively, found in stone marten (Martes foina) and fox (Vulpes vulpes). Data from this study provided information on baseline levels of interest to monitor status and trends in chemical residue in biota in this specific area, and therefore they represent a tool to evaluate potential ecologic, wildlife, and human health exposure.

Microcanalization in the epididymis to overcome ductal obstruction caused by chronic exposure to chromium – a study in the mature bonnet monkey (Macaca radiata Geoffroy)

In order to apprehend the toxic effects of chromium, an occupational/environmental pollutant, on the epididymis, adult bonnet monkeys were exposed to chromium (VI) in their drinking water at concentrations of 100, 200 and 400 p.p.m. for a chronic period of 180 days. At the end of the experimental period, testicles and segments of epididymis from control and treated monkeys were subjected to light microscopic (resin-embedded semi-thin sections) and transmission electron microscopic analyses. Among the various changes undergone by the epididymal epithelium, the present paper describes the origin of two different kinds of microcanals, probably caused by ductal obstruction. The first type of microcanal, which appears to provide passage for spermatozoa to bypass the obstructed main duct, is comparable with the one already reported in carbendazim-treated efferent ductules of the rat. The second type of microcanal, which is novel, consisted of a lumen in the epithelium enclosed by four to five cells, which are either modified basal cells, principal cells or a hitherto unknown cell type. This novel type of microcanal is suggested to be a device to entrap the spermatozoa which reach the core of the epithelium and may be a mechanism to prevent extravasation of sperm so as to avoid an autoimmune response of spermatic granuloma formation. Thus, the present study has shown that chronic exposure to chromium (VI) through drinking water can produce pathological manifestations in the epididymal epithelium but the epididymis, being a versatile organ, is capable of overcoming such adverse situations through novel devices.